Re: [Steam]-y Thread XXX: Throwing titles out the window!

Eeeeeven then most of them aren't. The ubersaw is likely the only one that is, and even then the bonesaw has it's place. I still run with the needlegun rather than bluts in most cases (:

I would say the degreaser/axetinguisher combo is a straight upgrade though, purely because of sheer damage output possible with it.

Neither of those are "straight upgrade." A straight upgrade has an improvement without any sort of disadvantage to offset it. The two examples I can think of (although I know there are a few more) are the Amputator and the Third Degree.
The amputator has the exact same stats as the standard bonesaw, with the addition of a taunt that can heal multiple allies at once. The Third Degree has the same stats as the Fire Axe, but damages any medic healing your target.
Interestingly enough, neither of the "straight upgrades" are frequently used. The Amputator taunt is so situational and makes you so vulnerable that there's almost never any point to using it instead of the ubersaw or the vita-saw. The only conceivable reason for using it is the healing regen you get as part of its set, not because the taunt itself is particularly useful.
With the Third Degree, you're better off with the degreaser/axetinguisher combo in nearly every case due to the vastly increased damage potential. However, neither the axetinguisher nor the degreaser can properly be called "straight upgrades" even though they're used by almost all players almost all of the time. The degreaser has a reduction in afterburn damage, and the axetinguisher deals no random crits or something trivial like that.

With very few exceptions, the vanilla weapons will provide you with the best results in the most likely situations. They also generally have higher skill ceilings, a plus if you intend to get into competitive play or even if you just want to get better.